Electrical apparatus



Oct. 22, 1940. H. HAAS 2,218,748

ELECTRICAL APPARATUS Filed April 6. 1939 INVENTOR.- fiaro/d Haas Patented Oct. 22, 1940 UNITED STATES PATENT OFFICE ELECTRICAL APPARATUS poration of Delaware Application April 6, 1939, Serial No. 266,404

1 Claim. (CL 171-229) This invention relates to electrical apparatus, and particularly to the regulation of the voltage output of a direct current generator.

Direct current generators whose capacity is 5 sufiiciently high to produce field current flow in excess of a few amperes present a problem in voltage output regulation which is not satisfactorily met by use of vibrating regulators connected in the manner that has become standard in automotive vehicle installations which-until a very recent datedid not involve generator loads in excess of, say, fifty amperes, or voltage outputs in excess of fifteen to thirty volts.

Recent developments in the automotive field, particularl in the design of buses,-aircraft and marine craft to transport heavier loads under power developed by internal combustion engines, have involved constantly increasing demands for generation of more electrical power by use of 23:) engine-driven generators of higher capacities than heretofore. The result has been to create a problem in satisfactory voltage regulation.

It is accordingly an object of the present invention to provide, in a generator system ineluding a voltage regulator of the vibratory type,

novel means for protecting the vibratory contacts against exposure to the full current capacity of the generator field, the strength of which said contacts are adapted to regulate. Another object is to provide this protection of the contacts against exposure to currents of high amperage by a method, and by use of means, which lengthens the life of the contacts without at the same time sacrificing anything in the matter of efilciency of the voltage regulating action, as compared with that of similar vibratory regulators heretofore employed.

These and other objects of the invention will become apparent from inspection of the following specification when read with reference to the accompanying drawing wherein is illustrated the preferred embodiment of the invention. It is to be expressly understood, however, that the drawing is for the purpose of illustration only, and are not designed as a definition of the limits of the invention, reference being had to the appended claim for this purpose.

In the drawing reference characters 5 and 6 designate'the armature and shunt field windings,

respectively, of a direct current generator to supply current.to devices (not shown) by way of positive and negative feeds 1 and 8, respectively, across which feeds are tapped the windings 9 and ill of a vibratory armature type of voltage 65 regulator, the vibratory armature l I being shown as having its contact point l2 biased to the circult closing position by spring means 13. A third winding l4, responsive to line current and operating to modify the frequency of vibration of armature ll, may or may not be included in the 5 voltage regulator assembly, asdesired. On each opening of the vibrating contact l2 the resistance I6 is effective in the conventional manner to vary the strength of the shunt field and there by tend to restore the predetermined voltage 10 across the lines I, 8; but injury to or excessive wear upon the contacts 12 is prevented by limiting current flow to said contacts in the novel manner now to be described.

A relay 2| has its winding. interposed in the 15 circuit to generator field 8, and its armature 22 provided with a contact biased away from a fixed contact 23 by spring means 24, but movable to engage said contact 23 whenever the current in field circuit 6 exceeds the predetermined value, :0 as regulable by the tensioning of spring 24--it being understood that armature 22 is in the magnetic field of coil 2|. The closing of contacts 22, 23 thus diverts from regulator contacts I! (andintervening connections ll, I9, 2|) all field 88 current in excess of that which is considered safe for the contacts I2 to handle without undue erosion. If desired, a condenser 3| and resistor 32 may be connected in shunt with contacts 22, 23 to reduce arcing across the latter.

From the foregoing it will be understood that when the generator is started the contacts of the auxiliary field regulator 2| close and remain closed as long as the field current is heavy; but, as the field current now has a direct path to the 35 windings 6 (by way of contacts 22, 23) the tendency will be for less current to flow in the path l2, H, is, 2|. Consequently the resultant weakening of the field about relay 2| will permit spring 24 to re-open the contacts 22, 23; whereupon the 40 current fiow through winding of relay 2i will again increase and cause a repetition of the cycle. The result is a vibratory action of the a mature of relay 2!, at a frequency which is suflicient to hold the current flow through the voltage regula- 45 tor circuit to a reasonably low value, and thus avoiding excessive erosion of the contacts at l2. Meanwhile the voltage regulator armature H continues to vibrate and control the generator voltage, in the conventional manner.

What I claim is:

In a generator system including armature and shunt field windings, a resistance element, and a vibratory type of voltage regulator having a winding connected across the armature terminals and a contact in series with said shunt field winding and movable to alternately cut said resistance element in and out of the shunt field circuit in accordance with voltage changes across said armature terminals, means for diverting from said regulator contacts that portion f the field circuit current which exceeds a. predetermined value, in" amperes, said diverting means including a relay having a winding forming part of said shunt field circuit and interposed in said circuit between said voltage regulator contact and in series with the shunt field winding, and also having its armature in parallel relation to said regulator contacts, to shunt the generator shunt field current from the latter whenever said current issufliciently high to move said armature to current shunting position; and means of preadjusted strength to yieldably oppose movement of said relay armature to the current shunting position.

HAROLD HAAS. 

